ST. PAUL, Minn. – The surest place to find Michele Bachmann on Sundays this summer is at a worship service somewhere in Iowa, offering the testimony of a Republican presidential candidate who has long tied her political beliefs to her faith.

While she isn't the only conservative Christian in the field, Bachmann has vaulted into the top-tier of candidates seeking the GOP nomination in no small part by tapping the enthusiastic support of evangelicals and social conservatives in the early voting states of Iowa and South Carolina.

But a new spiritual primary looms. Texas Gov. Rick Perry is entering the race and, like Bachmann, he is a devout Christian whose faith defines his politics. Perry's well-publicized appearance at a Houston prayer rally attended by 30,000 people last weekend won strong reviews, and there are already signs that Bachmann is starting to take steps to protect her early hold on the party's base of faith-driven voters.

"For that group of voters, they will be battling it out," said David Roederer, who held top Iowa posts in John McCain's 2008 campaign and George W. Bush's 2000 bid.

Bachmann's campaign won't discuss how Perry's entry into the race affects their strategy. But on the eve of the Texas prayer rally, her team sent reporters a roster of supporters containing more than 100 pastors and spiritual leaders in Iowa.

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She has been highlighting her faith-based backers more heavily and swapped out a planned trip to New Hampshire for one to South Carolina, a state where she and Perry would likely compete directly for votes among social conservatives.

Perry makes his debut trip to Iowa on Sunday for an event in Bachmann's birthplace of Waterloo; Bachmann said Thursday she would appear at the same party fundraiser that night.

Along with Perry, Bachmann is competing with former Pennsylvania Sen. Rick Santorum and former Minnesota Gov. Tim Pawlenty for votes among faith-driven voters. The race is the first in Bachmann's political career in which she's been forced to complete for such support; her Minnesota campaigns regularly mixed faith and policy, and social conservatives were always a crucial part of her base.

"We are in the last days," Bachmann prayed from a Minnesota stage in 2006, the year she was first elected to Congress. She asked God during that appearance to help foster the success of You Can Run But You Can't Hide, a Minnesota ministry led by Bradlee Dean, a pastor who has been repudiated even by Republicans for calling gays "predators," among other things.

In that appearance, Bachmann praised the ministry's outreach to public schools and its attempt to explode notions about the separation of church and state, which she called "a myth."

This summer, while aggressively chasing support from Iowa voters who put a premium on social issues such as fighting abortion and gay marriage, Bachmann has also tried to guard against being cast as someone with limited appeal. In Council Bluffs this week, she portrayed herself as a candidate who can stitch varied GOP constituencies — not just those driven by faith — into a winning coalition.

"It is a movement that is being heard all across the country. It is made up of fiscal conservatives, and I'm one of those. It's made up of peace-through-strength, national-security conservatives. I'm one of those," she said. "It's made up of social conservatives. I'm one of those. And it is made up of the glorious tea party movement, and I'm one of those."

Raised in the Lutheran church, Bachmann has said she was born again at age 16 and has rarely made a major decision since without direction from God. She and her husband, Marcus, she said, realized they would marry after God gave them simultaneous visions. She would go on to feel God's hand in decisions to attend law school, have children and take in foster children, seek political office and, ultimately, run for president.

For many years, the Bachmanns attended a Wisconsin Evangelical Lutheran Synod church near their home in Stillwater, Minn. The conservative denomination adheres to a strict doctrine that some have called anti-Catholic — Bachmann has disavowed those views — and excludes women from church leadership roles.

The family formally left the church around the time Bachmann launched her presidential campaign and now attends an evangelical mega-church in suburban St. Paul. But even some Bachmann supporters wonder if the views held by some in similar evangelical congregations might open the door for Perry to indirectly siphon away some of her backers.

"I don't know a lot about Rick Perry," said Bachmann supporter Julia Anderson, the wife of an evangelical pastor and a stay-at-home mom in Hubbard, Iowa. "I would say the one thing that, sadly, is going to maybe be a test for her is the fact that he's a man and she's a woman. I've had people say, 'What are you doing supporting a woman candidate? That's upsetting the order of the home.'"

Bachmann supporter Danny Carroll, a former Iowa legislator active in social conservative circles, said Perry's arrival shouldn't mean Bachmann needs to do more to stress her own faith. He cautions that in doing so, candidates can go too far.

"The more you have to tout and promote your Christian beliefs, in some respects, the more suspect it becomes," Carroll said.

Roederer, the former Bush and McCain adviser, said Bachmann seems to hold the early advantage over Perry because she's invested more time forging personal bonds in Iowa. But the Rev. Marcus Moffitt of the Calvary Baptist Church in northwestern Iowa, and among those on Bachmann's list of supportive pastors, said he's still open to other candidates — including Perry.

"I appreciate a number of things that Perry has done as Texas governor related to social issues and textbooks and different things like that," Moffitt said. A backer of caucus winner Mike Huckabee in 2008, Moffitt said he'd ultimately vote for the candidate who is "most willing to pursue their convictions regardless of how the political winds blow."

"Primarily," he said, "I want to see strength of leadership on moral issues."